Page 376 - Defrosting for Air Source Heat Pump

Index 373

fin surface temperatures, 179, 181–182f, air temperature, 162f, 164
186 ASHP unit, 155–156
frost accumulations, 176, 177f COP variation, 163f, 164
melted frost temperatures, 179, even frosting, control method of,
183–185f, 187–188 156–157
refrigerant volumetric flow rate, 185f, experimental cases, 155–157, 159t
188 fin surface temperatures, 163f, 164
tube surface temperatures, 179–183, refrigerant pressure drop, 159–160, 161f,
180–181f 162–163
refrigerant volume flow rate, 156–157,
159–160, 161f, 162–163
M tube surface temperatures, 156–157,
Mal-defrosting, 36, 273 157–158f, 159–162, 160f, 162f
Manual stop valve (MV), 48
Melted frost, 52–53, 57–58 O
Melted frost downward flowing (MFDF), 204 Outdoor coil. See also Uneven defrosting
Melted frost elimination, on uneven in ASHP unit, 5–7
defrosting, 116–135 defrosting process, 33, 33f
airside surface conditions of outdoor coil, frost-suppression measures
119, 120f, 124–126, 125f, 127f coating treatment on fin surface, 18–19,
ASHP unit, 118–121, 120t 20–21t
defrosting duration, 132–134, 133–134t
fin and tube geometry adjustment, 17–18
defrosting evenness coefficient, 132, 133t
fin-type adjustment, 18
energy performance analysis, 134, 135t
increasing inlet airflow rate, 16
experimental cases, 122–124
preheating inlet air, 13–16
experimental conditions, 121–122, 121t,
reducing inlet air humidity, 13
124t
multicircuit outdoor coil, 193–194,
fin surface temperatures, 126, 129–130f,
200–201, 204–205, 303–304,
131–132 321–322, 324, 338–339
force analysis of retained water droplets,
123, 123f
P
horizontally installed three-circuit outdoor
Payback period, 303–304, 324, 340
coil, 119f
Phase change materials (PCM), 29
mass transfer of retained water, 123–124,
Photocoupler, 36
124f
Polyvinyl chloride (PVC), 48
measurement/calculation errors, 121–122,
122t
three-circuit outdoor coil, 118, 119f, 120t R
tube surface temperatures, 126–131, RCD. See Reverse cycle defrosting (RCD)
128–129f Refrigerant charge compensator, 28
vertically installed outdoor coil, 117f Refrigerant distribution, 344
Metal energy storage (MES) effect, 349 defrosting performance
Moving boundary technique, 33 energy analysis, 202–204
Multicircuit outdoor coil, 193–194, 200–201, experimental cases, 194–197
204–205, 303–304, 321–322, 324, experimental results, 197–202
338–339 downward-flowing melted frost, 193
frosting evenness coefficient gravity and tube internal resistance,
airside surface conditions, 154, 155f, 193–194
158, 159f gravity force, 193–194